Add a public initializer to RenderContentMetadata

Sources/SwiftDocC/Model/Rendering/Content/RenderContentMetadata.swift

@@ -20,6 +20,19 @@ public struct RenderContentMetadata: Equatable, Codable {
     public var abstract: [RenderInlineContent]?
     /// An optional identifier for the device frame that should wrap this element.
     public var deviceFrame: String?
+
+    /// Creates a new metadata value for a content element.
+    /// - Parameters:
+    ///   - anchor: The named anchor of the content element.
+    ///   - title: The customized title for the content element.
+    ///   - abstract: The customized abstract for the content element.
+    ///   - deviceFrame: The identifier for the device frame that should wrap the content element.
+    public init(anchor: String? = nil, title: String? = nil, abstract: [RenderInlineContent]? = nil, deviceFrame: String? = nil) {
+        self.anchor = anchor
+        self.title = title
+        self.abstract = abstract
+        self.deviceFrame = deviceFrame
+    }
 }
 
 extension RenderContentMetadata {

Tests/SwiftDocCTests/PublicAPI/PublicAPITests.swift

@@ -0,0 +1,27 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2025 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See https://swift.org/LICENSE.txt for license information
+ See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+// Import SwiftDocC without the @testable annotation, so we can test
+// whether various API are actually public.
+import SwiftDocC
+
+import XCTest
+
+class PublicAPITests: XCTestCase {
+
+    func testPublicRenderContentMetadataInitializer() throws {
+        let _ = RenderContentMetadata(
+            anchor: "anchor",
+            title: "title",
+            abstract: [],
+            deviceFrame: "device frame"
+        )
+    }
+}